I know summer is on its way so i might wait to do it but I have a godspeed radiator and a 3K cfm flexalite 20+ amp fan cooling my T-2. Havent really driven it too much over the winter but the temp never gets over 1/4 of the way, even doing a monster boostes run up to the georgia line. I was going to put a Thermostat on the fan but was wondering the ideal temp to set it at , i figure 160, but would like opinions. The only reason i even want to do this is i suspect that I am going to get better gas mileage if it reaches full operating temperature, if this is not the case then there is no reason for me to change the way its setup now. Any info is always appreciated.

 

The factory thermostat begins to open at about 82C/180F and opens fully at 95C/203F . So really anything between that is fine. I certainly wouldn't run it cooler than 180F, and I wouldn't turn a fan on until like 190. Running any cooler than 180F might in some cases result in cold oil temps (improper viscosity and engine clearances) and worse fuel economy.

Here are some interesting results from brake-specific fuel consumption tests done on a NASA 12A turbo research engine:


Meng, "Preliminary Results on Performance Testing of Turbocharged Rotary Combustion Engine," 1982

 

First, get a real water temp gauge..."a quarter up the scale" is archaic (like "fathom" and "dollar").
A gauge that reads Fahrenheit or Celcius will do nicely.

Given the operating range of the stock thermostat, I chose 195°F as the trigger point for the low speed of the fan. High speed activates at 205°F.
High speed rarely kicks in during my daily routine, YMMV.

 

Thanks gang. I will get a real temp gauge + thermostat this week. Just for reference. When i start in the morning the AFR's are 11.5 , after I driver about a mile they start bouncing between 14.5-15 so something must be changing the open loop mode. Could be that the stock temp gauge is simply off. Guess a real one would tell me more. Also , im surprised they run hot like a SBC. Im used to my BMW's running 180-190

 

Interesting data indeed. So, taking my 281.40 lbs/hr fuel flow (4x720cc injectors @43 psi) X .90 DC (max) / ~.65 BSFC ( @7000 RPM and assuming my engine is not perfect like the NASA sample) ~= 390 BHP potential. I can live w/ that!

 

on an S4 the gauge is accurate, its just not labeled... i'd consider a "real" gauge optional.

the AFR's from a cold start will be rich, and it should lean out as it warms up. when an engine is cold, fuel doesn't atomize very well, so the mixture needs to be richer. every car does this to varying degrees.

the closed loop is turned on by the switch in the bottom of the radiator @about 65C.

i think if you look you'll find that every engine wants something a little different for coolant temps, for example the new BMW turbo motor runs coolant, oil and EGT's that would melt a rotary....